This invention relates to a flush mounted, self-flashing skylight to be mounted on a roof of inclined slope. More particularly, this invention relates to a flush mounted, self-flashing skylight for mounting on roofs of inclined slope where the skylight is free floating in the flashing to allow for thermal expansion and contraction of the skylight relative to the flashing when the flashing is permanently attached to the roof structure.
There have been many designs for improving conventional skylights. Many of the problems have been associated with providing adequate sealing of the skylight structure to the roof without leaking. The configuration of conventional skylights is generally rectangular with the skylight itself being flat or convexly curved. Most skylights are made of a light-transmissive material which may be clear or translucent. Most are made of a high impact, thermally expandable, plastic such as acrylics, polycarbonates and the like. Some are also made of glass. Most skylights are mounted in a framework or curb that is to be inserted through the roof structure. Some units have been stated to be "self-flashing" in that the skylight unit contains outwardly extending flanges over which is laid the roofing material to provide a more waterproof joint between the skylight and the roof. However, because most skylights are domed structures, rain water is often deflected around and down the skylight toward the edges where the joints between the skylight and the roof may permit leakage. This is stated to be particularly troublesome at the bottoms of skylights since water running over the skylight may be directed under the roofing material. U.S. Pat. No. 4,548,006 attempts to overcome this problem by providing a self-flashing structure wherein the skylight has flanged side edges and a raised lower end. Rain water is directed down the skylight between the raised flanges and "ski jumps" over the raised end. However, this doesn't really solve the leaking problem since water that doesn't "ski-jump" off the end, falls directly at the juncture of the skylight and the roofing shingles. Since the shingles overlap the skylight flanges, water can still work its way under the shingles.
Various methods of providing sealing around skylights are taught in the art. Conventionally, a skylight is secured to a roof with the use of roofing mastic consisting of an asphaltic or resinous material. A roof opening is made, the roofing mastic applied on the deck around the opening and the flange, surrounding the curb frame to which the skylight is attached, is placed over the mastic and firmly pressed to create a seal. The flange is nailed to the roof and additional mastic is applied. Shingling is then completed around the skylight curb frame.
This method is messy and not very effective unless properly done. It is difficult for a "do it yourself" application because the seal between the mastic and the curb frame must be perfect if leakage is to be avoided. Various means to improve upon the conventional method are disclosed in U.S. Pat. Nos. 3,455,073; 4,527,368 and 4,589,238. However, none of these relate to flush mounted skylights in that all are contained on a curb frame that extends above the roof surface.
A single pane skylight is disclosed in U.S. Pat. No. 4,173,854 which requires the use of bow members having convex upper edges over which is placed flashing which must be accurately bent at various angels to accommodate the convex upper surface and vertical side surface of the bow members and also the flat rafter or sheathing surface on which the bow members rest. Also, the light transmitting skylight cover itself must be oversized relative to the roof opening and secured to the roof surface with screws or other fastening means. Unless very accurately installed, the attachments of the skylight cover and flashing present numerous leakage problems. For example, the thermal expansion and contraction of the plastic skylight cover can cause the screws, with which it is secured to the roof, to work loose and cause leakage.
Provisions for thermal expansion or contraction are not generally made in prior art devices. A rolling seal arrangement to provide for thermal expansion in skylights mounted in a curb frame is described in U.S. Pat. No. 3,455,073.
Although there is considerable art in skylight technology, there has not heretofore been available a simple, inexpensive, self-flashing, water-tight, flush mountable dual pane skylight.